One of the problems associated with hip, knee and foot surgery is a loss of sensation in the affected limb. Although the limb may be physically whole and the associated muscles are controllable, visual confirmation of contact between the foot and the ground is necessary. Visual confirmation is also essential in the case of amputation of the limb and certain degenerative conditions due to medical circumstances, eg: diabetes, frostbite, obesity.
Those without sensation in the lower limbs also experience difficulty in operating machinery where vision has to be concentrated on the machine in use, eg: motor vehicle, yard equipment. Activities such as negotiating steps and ladders, stepping backwards, responding to moving objects (e.g.; crossing a road in traffic), walking in darkness or on uneven surfaces and carrying large objects are made much more difficult without sensory feedback from the feet. Quite often, the post-surgical medication given to the patient reduces the patient's ability to concentrate visually on the movement of the feet.
There are also certain medical conditions which preclude a patient from looking downwards to check each step taken, e.g., progressive supranuclear palsy (PSP) and certain balance disorders.
Although there are devices available which will indicate pressure on the foot, they are designed for gait corrective therapy in a clinical environment and are not intended for everyday use. In reality, the only existent remedy for those affected, is to use a cane, or, in the worst cases a wheelchair.